This invention relates to synchrotrons, which are devices for increasing the energy of charged particles by causing them to travel in a curved path and thereby pass repeatedly through a radio frequency accelerating cavity. Synchrotrons are used for a number of research and manufacturing applications using either the charged particles or the radiation which they emit. In one application the charged particles are electrons which are made to emit radiation in the "soft" X-ray range, having wavelengths in the range 1 Angstrom to 100 Angstrom, the radiation being given off at a tangent to the path of the electrons and, therefore, being emitted as an arc-shaped beam of narrow angle in the transverse direction.
In order to produce radiation in this range using conventional resistive electromagnets, the size of the synchrotron has to be fairly substantial and, for example, to produce the frequency of radiation required for X-ray lithography in a synchrotron using electrons, the synchrotron would have to be of the order of ten meters in diameter or more.
The use of superconductors to produce the magnetic field needed to deflect the electrons in the required curved path would reduce the size of the device substantially but it would, nevertheless, still be quite large and would still be expensive to manufacture. For example, it has been proposed to make the superconducting coils circular and to contain the radio frequency accelerating cavity within the aperture of the coils. However, because the radio frequency cavity must be of substantial size, the size, weight, force level and stored energy of the magnet system would all be correspondingly large and, therefore, expensive to manufacture. Of particular concern would be the requirement for a large power supply, arising from the large amount of magnetic energy the system would store.
The present invention seeks to minimize the magnet size, weight, force level and stored energy by using a design which is extremely compact.